1. Field of the Invention
The present invention relates to compositions containing mixtures of catenate and cyclic siloxane oligomers of the formulae I and II: 
where the R substituents comprise both alkoxy groups and organofunctional groups, and where not more than one organofunctional group is attached to one silicon atom.
The present invention also relates to a process for preparing the mixtures and to their use in a variety of applications.
2. Description of the Background
Mixtures of catenate and cyclic siloxane oligomers are obtained, for example, by controlled hydrolysis or condensation of organofunctional alkoxysilanes. A particular problem when preparing multifunctional siloxane oligomers is the highly differing hydrolysis or condensation behavior of the individual organoalkoxy or organochlorosilanes.
EP 0 716 128 A2, EP 0 716 127 A2 and EP 0 675 128 2 A1 disclose aqueous solutions of amino-functional and CH-containing organosilanes and organosiloxanes. In these organosilane systems, hydrolysis is virtually complete.
EP 0 518 057 A1 and DE 196 24 032 A1 disclose mixtures of catenate and cyclic vinyl- and also alkyl-functional siloxane oligomers which also carry alkoxy groups. Such mixtures are employed, for example, to hydrophobicize mineral surfaces and pulverulent substances, and as crosslinking agents for thermoplastic polyolefins.
German patent application serial number 198 34 990.4 describes mixtures of catenate and cyclic acryloxypropyl- or methacryloxypropyl-functional siloxane oligomers.
Such siloxane oligomer mixtures can be used, for example, for the surface treatment of mineral surfaces or pulverulent substances, such as titanium dioxide, talc, clay, silicas, quartz, kaolin, aluminum hydroxide, magnesium hydroxide, bentonite, montmorillonite, mica (muscovite mica), calcium carbonate (chalk, dolomite), for example. These siloxane oligomer mixtures are also employed as adhesion promoters in, for example, kaolin-filled rubber compounds.
However, there still remains a need for new compositions containing siloxane oligomers.
It is an object of the present invention to provide novel organofunctional siloxane oligomer mixtures, containing amino-functionalized siloxane compounds.
It is another object of the invention to provide methods of making the mixtures.
It is another object of the invention to provide methods of using the mixtures for a variety of purposes.
The objects of the invention, and others, may be accomplished with a mixture of catenate and cyclic siloxane oligomers of the formulae I and II: 
where the substituents R are
(i) aminopropyl-functional groups of the formula xe2x80x94(CH2)3xe2x80x94NH2 or xe2x80x94(CH2)3xe2x80x94NHRxe2x80x2 or xe2x80x94(CH2)3xe2x80x94NH(CH2)2xe2x80x94NH2 or xe2x80x94(CH2)3xe2x80x94NH(CH2)2xe2x80x94NH(CH2)2xe2x80x94NH2, in which Rxe2x80x2 is a linear, branched or cyclic alkyl group of 1 to 18 carbon atoms or an aryl group of 6 to 12 carbon atoms, and
(ii) methoxy, ethoxy, 2-methoxyethoxy and/or propoxy groups, and
(iii) if desired, alkyl, alkenyl, isoalkyl or cycloalkyl groups of 1 to 18 carbon atoms and/or aryl groups of 6 to 12 carbon atoms,
where
not more than one aminopropyl-functional group is attached to one silicon atom,
the degree of oligomerization of compounds of the formula I is within the range 2 less than m less than 30 and that of compounds of the formula II is 3xe2x89xa6nxe2x89xa630, and the quotient of the molar proportion of Si/alkoxy group is xe2x89xa70.5.
Such mixtures may be obtained by a controlled reaction using at least one aminopropyl-functional trialkoxysilane or one aminopropyl-functional methyldialkoxysilane as component A and, if desired, at least one alkyl-, alkenyl-, isoalkyl- or cycloalkyl-trialkoxysilane of 1 to 18 carbon atoms and/or phenyltrialkoxysilane and/or alkyl-, alkenyl-, isoalkyl- or cycloalkyl-methyldialkoxysilane of 1 to 18 carbon atoms and/or phenylmethyldialkoxysilane as component B and, if desired, a tetraalkoxysilane as component C, subjecting the components A andxe2x80x94if usedxe2x80x94B and C in succession or in a mixture to controlled hydrolysis and condensation using from 0.6 to 1.2 mol. of water per mol. of Si and from 0.1 to 5 times the amount by weight of methanol and/or ethanol, based on the alkoxysilanes employed, at a temperature from 10 to 95xc2x0 C. and subsequently working up the product mixture by distillation under atmospheric pressure or under reduced pressure and at a liquid-phase temperature of up to 120xc2x0 C. In the course of this distillation the free alcohol and any residues of the unhydrolyzed monomeric starting materials are suitably removed from the product. It is possible, accordingly, to provide a further amino-functional siloxane oligomer mixture. A particular advantage is that the hydrolysis or condensation can be carried out in a controlled manner without an additive alien to the system, such as a hydrolysis or condensation catalyst.
The objects of the present invention may also be accomplished with methods of using the compositions containing the siloxane mixtures described above. Such methods of use include the following:
(1) a method of improving the adhesion properties of adhesives and sealants, by incorporating the composition into an adhesive or a sealant,
(2) a method of modifying organic resins, by contacting an organic resin with the composition,
(3) a method of crosslinking organic resins, by contacting the organic resins with the composition,
(4) a method of providing binders in inks and coatings, by incorporating the composition into an ink or a coating,
(5) a method of coating glass fibers, by applying the composition to glass fibers,
(6) a method of promoting adhesion in filled thermoplastic compounds, by incorporating the composition into the filled thermoplastic compounds,
(7) a method of treating mineral, organic and metallic surfaces, by applying the composition to a mineral, organic or metallic surface,
(8) a method of hydrophobicizing surfaces, by applying the composition to a surface, and
(9) a method of surface modifying pulverulent substances, by applying the composition to the surface of a pulverulent substance.
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description.
Resultant mixtures of the invention comprising catenate and cyclic siloxane oligomers are normally homogeneous, clear, colorless to pale yellow liquids of low viscosity which are stable on storage and preferably have a flash point greater than 100xc2x0 C.
By means of the procedure described above it is possible advantageously to produce siloxane oligomers of the invention possessing, preferably, a statistical distribution of [xe2x80x94Si(R)(R)Oxe2x80x94] units of different functionality.
It is also advantageous that the boiling point of the mixtures of the invention comprising catenate and cyclic siloxane oligomers is generally at a temperature  greater than 200xc2x0 C.
The present invention therefore provides a mixture of catenate and cyclic siloxane oligomers of the formulae I and II: 
where the substituents R consist of
(i) aminopropyl-functional groups of the formula xe2x80x94(CH2)3xe2x80x94NH2 or xe2x80x94(CH2)3xe2x80x94NHRxe2x80x2 or xe2x80x94(CH2)3xe2x80x94NH(CH2)2xe2x80x94NH2 or xe2x80x94(CH2)3xe2x80x94NH(CH2)2xe2x80x94NH(CH2)2xe2x80x94NH2, in which Rxe2x80x2 is a linear, branched or cyclic alkyl group of 1 to 18 carbon atoms or an aryl group of 6 to 12 carbon atoms, and
(ii) methoxy, ethoxy, 2-methoxyethoxy and/or propoxy groups, and
(iii) if desired, alkyl, alkenyl, isoalkyl or cycloalkyl groups of 1 to 18 carbon atoms and/or aryl groups of 6 to 12 carbon atoms,
and where not more than one aminopropyl-functional group is attached to one silicon atom and the degree of oligomerization of compounds of the formula I is within the range 2 less than m less than 30 and that of compounds of the formula II is 3xe2x89xa6nxe2x89xa630 and the quotient of the molar proportion of Si/alkoxy group is xe2x89xa70.5.
Thus, each R is independently selected from the group consisting of xe2x80x94CH2)3xe2x80x94NH2, xe2x80x94(CH2)3xe2x80x94NHRxe2x80x2, xe2x80x94CH2)3xe2x80x94NH(CH2)2xe2x80x94NH2, xe2x80x94CH2)3xe2x80x94NH(CH2)2xe2x80x94NH(CH2)2xe2x80x94NH2, methoxy, ethoxy 2-methoxyethoxy, propoxy, alkyl, alkenyl, isoalkyl and cycloalkyl groups having 1 to 18 carbon atoms, and aryl groups having 6 to 12 carbon atoms,
with at least one R is an aminopropyl-functional group selected from the group consisting of xe2x80x94(CH2)3xe2x80x94NH2, xe2x80x94(CH2)3xe2x80x94NHRxe2x80x2, xe2x80x94(CH2)3xe2x80x94NH(CH2)2xe2x80x94NH2, and xe2x80x94(CH2)3xe2x80x94NH(CH2)2xe2x80x94NH(CH2)2xe2x80x94NH2 groups, and
with at least one R is selected from the group consisting of methoxy, ethoxy, 2-methoxyethoxy, and propoxy groups.
Mixtures of the invention comprising catenate and cyclic siloxane oligomers preferably have an alkoxy group content of more than 0.1% by weight and less than 50% by weight, in particular less than 30% by weight, with particular preference from 5 to 25% by weight, based on the weight of the siloxane oligomers present. These weight % ranges include all specific values and subranges therebetween, such as 0.2, 0.5, 1, 2, 8, 10, 15 and 20% by weight.
In a mixture according to the invention, preferably, the substituents R consist of (i) aminopropyl, aminoethylaminopropyl, aminoethylaminoethylaminopropyl, methylaminopropyl, n-butylaminopropyl, cyclohexylaminopropyl and/or phenylaminopropyl groups and (ii) methoxy, ethoxy, 2-methoxyethoxy and/or -propoxy groups, and (iii) optionally, methyl, vinyl, ethyl, propyl, isobutyl, octyl, hexadecyl or phenyl groups.
As examples, preferred systems of catenate and cyclic siloxane oligomers include the following: 3 -aminopropyl-/n-propyl-/alkoxy-siloxanes; N-aminoethyl-3-aminopropyl-/n-propyl-/alkoxy-siloxanes; N-butyl-amino-propyl-/methyl-/alkoxy-siloxanes, where the alkoxy groups are preferably methoxy or ethoxy groups although it is also possible for ethoxy and methoxy groups to be present alongside one another.
The present invention also provides a process for preparing a novel mixture of catenate and cyclic siloxane oligomers by controlled hydrolysis using at least one aminopropyl-functional trialkoxysilane or an aminopropyl-functional methyldialkoxysilane as component A and, if desired, at least one alkyl-, alkenyl-, isoalkyl- or cycloalkyl-trialkoxysilane of 1 to 18 carbon atoms and/or phenyltrialkoxysilane and/or alkyl-, alkenyl-, isoalkyl or cycloalkyl-methyldialkoxysilane of 1 to 18 carbon atoms and/or phenylmethyldialkoxysilane as component B and, if desired, a tetraalkoxysilane as component C, subjecting the components A andxe2x80x94if usedxe2x80x94B and C in succession or in a mixture to controlled hydrolysis and condensation using from 0.6 to 1.2 mol of water per mole of Si and from 0.1 to 5 times the amount by weight of methanol and/or ethanol, based on the alkoxysilanes employed, at a temperature from 10 to 95xc2x0 C. and subsequently removing the alcohol employed, and that liberated during the reaction, from the product mixture by distillation under atmospheric pressure or reduced pressure and at a liquid-phase temperature of up to 120xc2x0 C.
For the preparation of novel mixtures it is possible to startxe2x80x94for example but not exclusivelyxe2x80x94from the following compounds, or from mixtures of these compounds:
For Component A
3-aminopropyltrialkoxysilanes, N-aminoethyl-3-aminopropyltrialkoxy silanes, N-aminoethyl-N-aminoethyl-3-aminopropyltrialkoxysilanes, N-methylaminopropyl-trialkoxysilanes, N-n-butylaminopropyltrialkoxysilanes, N-cyclohexylamino-propyltrialkoxysilanes, N-phenyl-aminopropyltrialkoxysilanes, 3-aminopropyl-methyldialkoxysilanes, N-aminoethyl-3-aminopropyl-methyldialkoxysilanes, N-aminoethyl-N-aminoethyl-3-aminopropyl-methyldialkoxysilanes, N-methyl-aminopropyl-methyldialkoxysilanes, N-n-butyl-aminopropylmethyldialkoxysilanes, N-cyclohexyl-aminopropylmethyldialkoxysilanes, N-phenyl-aminopropyl-methyldialkoxysilanes.
For component B
methyltrialkoxysilanes, ethyltrialkoxysilanes, n-propyltrialkoxysilanes, isobutyltrialkoxysilanes, n-octyltrialkoxysilanes, isobutyltrialkoxysilanes, n-octyltrialkoxysilanes, isooctyltrialkoxysilanes, hexadecyltrialkoxysilanes, phenyltrialkoxysilanes, vinyltrialkoxysilanes.
For component C
tetraalkoxysilanes, where abovementioned alkoxy groups are preferably methoxy and ethoxy.
In general, the process of the invention may be performed as follows:
Component A, component B if desired and component C if desired are generally introduced as initial charge into the reaction vessel. A solvent or diluent, such as methanol or ethanol, may be added to the alkoxysilane mixture. It is suitable in addition to add the calculated amount of water for the reaction appropriately with thorough mixing with, for example, stirring. Before or after the addition of water the reaction mixture can be heated and following the reaction the resultant product mixture can be worked up by distillation in the manner described. The distillative workup of the product mixture is preferably conducted under atmospheric pressure and/or reduced pressure at a temperature in the range from 50 to 120xc2x0 C.
In the process of the invention, components A, B and C are employed preferably in a molar ratio A:B:C of from 1:0:0 to 1:10:0, preferably from 1:0:0 to 1:4:0, or from 1:0:0 to 1:0:10, preferably from 1:0:0 to 1:0:4, or from 1:0:0 to 1:10:10, preferably from 1:0:0 to 1:4:4.
In the process of the invention it is also preferred to employ alkoxysilanes having methoxy or ethoxy groups in accordance with the alcohol that is used as solvent or diluent. The solvent or diluent used is also suitably methanol, ethanol or a mixture of methanol and ethanol. However, other alcohols or alcohol mixtures can also be used.
In the process of the invention the hydrolysis and condensation of the alkoxysilanes employed are conducted preferably under atmospheric pressure at a temperature from 10 to 95xc2x0 C., with particular preference at from 60 to 80xc2x0 C. The reaction is normally conducted under atmospheric pressure, although it may also be conducted under reduced pressure or under superatmospheric pressure. It is appropriate to allow the reaction mixture to react for from 2 to 8 hours before beginning the distillation workup of the product mixture.
Following distillative workup, the product of the invention contains preferably less than 5% by weight of the components A, B and C and, in particular, less than 1% by weight of free alcohols.
Novel mixtures of catenate and cyclic siloxane oligomers may be used in the ways set out as described below, which, however, represent only nonlimiting examples.
The present invention therefore provides for the use of a novel mixture of catenate and cyclic siloxane oligomers as a composition for surface modification of pulverulent substances, for silanization of finely divided inorganic fillers and pigments, and also for treating mineral, organic and metallic surfaces, such as concrete, aluminum, steel and plastics (including PVC and PMMA to name but a few), for example. For instance, a novel mixture of catenate and cyclic siloxane oligomers can also be employed advantageously for the hydrophobicization of surfaces. In these applications, and those described below, an amount of the composition effective to accomplish the desired effect is applied.
The present invention additionally provides for the use of a novel mixture of catenate and cyclic siloxane oligomers as adhesion promoters in filled thermoplastic compounds, examples being HFFR (halogen free flame retardants) compounds, in order to provide improved mechanical strength and improved electrical insulation properties.
The present invention provides, moreover, for the use of a novel mixture of catenate and cyclic siloxane oligomers as adhesion promoters in adhesives and sealants in order to provide improved service properties, especially controlled curing behavior, improved mechanical strength and improved moisture resistance.
The invention also provides for the use of a novel mixture of catenate and cyclic siloxane oligomers for modification and crosslinking of organic resins, as binders in coatings and inks having improved service properties. and for coating glass fibers, for improved adhesion of these glass fibers in plastics reinforced with them and for providing improved mechanical strength.
Particularly advantageous properties of the siloxane oligomer mixtures of the invention relative to monomeric aminofunctional silanes employed as standard are the heightened boiling point, the increased flash point, the reduced vapor pressure, the reduced amount of hydrolysis alcohol liberated in the course of use (VOC) and in particular, the chemical xe2x80x9cmultifunctionalityxe2x80x9d.
Having generally described this invention, a further understanding can be obtained by reference to certain specific examples which are provided herein for purposes of illustration only and are not intended to be limiting unless otherwise specified.